After electrology treatment, a black and blue mark indicates the insertion was deep.

• A. The insertion was deep
• B. The insertion was shallow
• C. Bleeding occurred
• D. No reaction

Answer: (A)

A black-and-blue mark shows ecchymosis from trauma to small vessels beneath the skin. When the needle insertion is deep, it can rupture dermal capillaries or nearby vessels, causing blood to leak into surrounding tissue and create a bruise. If the insertion were shallow, there’s less vessel injury, so you’d expect minimal discoloration—often just redness or slight swelling rather than a bruise. A bruise is a sign of tissue injury from the procedure, not active bleeding occurring at the moment, and it confirms some deeper penetration rather than no reaction.